Geocell and Discrete-Fiber Reinforcement of Granular Soils: A Review of Strength, Stiffness and Deformation Behaviour

Weak granular soils frequently possess inadequate shear strength, low stiffness and excessive deformation characteristics, limiting their suitability for foundations, pavements, embankments and retaining structures. Geocells and randomly distributed discrete fibers have emerged as effective reinforcement techniques for improving the engineering behaviour of such soils. This paper reviews previous laboratory, numerical, field and model investigations concerning geocell-reinforced, fiber-reinforced and composite-reinforced soil systems. Geocells improve soil performance through three-dimensional confinement, lateral restraint, stress redistribution and enhanced particle interlocking. Their effectiveness is influenced by cell geometry, reinforcement stiffness, infill density, embedment depth and loading conditions. Randomly distributed fibers develop tensile resistance through friction and mechanical interaction with soil particles, thereby increasing apparent cohesion, post-peak strength, ductility and energy absorption. Fiber performance depends strongly on length, content, aspect ratio, material type and soil density. Previous studies demonstrate that geocells generally provide greater bearing-capacity and settlement improvements than planar or randomly distributed reinforcement. However, fibers offer multidirectional reinforcement and improved ductility. Combining geocell confinement with discrete fibers can generate a beneficial composite mechanism in which global lateral restraint and local tensile bridging act simultaneously. The review identifies the need for additional studies on moisture effects, cyclic loading, durability, sustainable reinforcement materials and field-scale composite applications.